1. Field of the Invention
The present invention generally relates to an electric power distribution switching device and an accidental arc detector for detecting accidental arcs in the electric power distribution switching device. The detector includes at least one optical waveguide, which optical waveguide is located in the vicinity of live parts, and in which the light generated by an accidental arc and reaching the optical waveguide radially via its casing acts as a triggering or warning criterion.
2. Background Information
DD 271 397 A1 describes an optical waveguide or light guide accidental arc detector, which optical waveguide is located in the vicinity of power supply buses without any special mountings. FIG. 2 of this publication shows the optical waveguide accidental arc detector in contact against both narrow sides of a bus bar which has a rectangular cross section. However, this publication does not indicate in any additional detail how the optical waveguide can be fastened to the bus bar. In FIG. 3 of the above-referenced publication, the optical waveguide is wound around the bus bar. In this arrangement, there is a danger that the optical waveguide can break, in particular at the points of contact with the corners of the bus bar, or in the areas near these corners. This arrangement also results in a severe restriction of the bonding surface of the bus bar.
There are also disadvantages to a direct surface mounting of the optical waveguide, as described in further detail in DE 43 31 716 A1. This publication also illustrates and describes various arrangements of an optical waveguide accidental arc detector.
FIG. 1 shows an arrangement in which the optical waveguide is oriented essentially vertically and is wound around the three bus bars. Disadvantages of this arrangement are that the distance from the point of origin of an accidental arc can be different, and that the accidental arc does not always occur in the vicinity of the detector.
With the meandering orientation illustrated in FIG. 3, of course, the latter phenomenon cannot occur, but there is always a danger, as with all other orientations, that the relatively thin and barely visible optical waveguide may be damaged during installation or other activities.
The invention also teaches that the optical fibers are located on bulkheads and other flat contact surfaces in the vicinity of the bus bar, in which case the optical waveguide can be fastened by means of adhesive or by fastening elements such as fastening lugs or spacers.
One problem with this arrangement is that bulkheads or similar elements are not always located close enough.